"He's had 18 months where he has been carrying an injury and his body hasn't felt right," said County manager Jim McIntyre.

"That's the whole reason for us taking our time and getting it right this time.

"The operation has been done and Billy is coming back well now. The physio is delighted with him.

"So it's just a matter of ticking all the boxes. Once he's ready to go, he'll be able to perform at his maximum, which will be to the benefit of Ross County."

Mckay scored 62 goals in 141 appearances in his first spell with Caley Thistle after leaving Northampton Town.

But he only played 10 games for Wigan after being sold to the Latics, who sent him on loan to Dundee United, Oldham Athletic and back to Caley Thistle.

Finally, his contract was cut short at the English League One club so he could join County as they sought to replace Liam Boyce after their top scorer was sold to Burton Albion.

"Billy is a couple of weeks behind everybody else, but he's doing fantastically well," added McIntyre, who will be without Mckay as the Staggies start their Scottish Premiership campaign away to Dundee on Saturday.

"He will rejoin the first team for part of their sessions next week, then we need to get some games into him."